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Evidence of Branching Phenomena in Current-Driven Ionization Waves
Keith T K Loebner1, Thomas C Underwood1, Mark A Cappelli1
1High Temperature Gasdynamics Laboratory, Stanford University, Stanford, California 94305, USA.
Physical Review Letters
|November 10, 2015
Summary
Researchers observed two types of ionization waves in plasma, matching the magnetohydrodynamic Rankine-Hugoniot model for hydromagnetic shocks. This study validates theoretical models with experimental data, showing less than 8% deviation.
Area of Science:
- Plasma Physics
- Magnetohydrodynamics
- Shock Waves
Background:
- Magnetohydrodynamic (MHD) shocks are crucial in astrophysical and laboratory plasmas.
- The Rankine-Hugoniot model describes shock transitions but experimental validation for current-driven ionization waves is limited.
Purpose of the Study:
- To experimentally observe and characterize current-driven ionization waves.
- To verify the applicability of the magnetohydrodynamic Rankine-Hugoniot model to these waves.
- To quantitatively compare experimental data with theoretical predictions.
Main Methods:
- Utilizing a coaxial gas-fed plasma accelerator to generate pulsed currents.
- Conducting detailed measurements of thermodynamic and electrodynamic plasma state variables.
- Analyzing wave behavior across the ionization region.
Main Results:
- First fully consistent experimental observations of current-driven ionization waves.
- Confirmation of two wave types corresponding to upper and lower Hugoniot curve branches.
- Quantitative agreement with the quasisteady, one-dimensional theoretical model with <8% deviation.
Conclusions:
- Experimental results strongly support the magnetohydrodynamic Rankine-Hugoniot model for current-driven ionization waves.
- The study highlights the complex coupling of state variables in transient plasma systems.
- Validates theoretical predictions for hydromagnetic shock phenomena in laboratory plasmas.
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